Significant Fuel Savings and Emission Reductions by Improving Vehicle Air Conditioning

John Rugh National Renewable Energy Laboratory

Valerie Hovland Mesoscopic Devices

Stephen O. Andersen U.S. Environmental Protection Agency

15th Annual Earth Technologies Forum and Mobile Air Conditioning Summit April 15, 2004

Outline• Modeling approach

• Thermal comfort-based AC fuel use prediction

• Model updates

• Fuel saved for up to 30%drop in AC power (equal to a43% increase in COP)

• Per vehicle (cars, light trucks) • By climate • Total savings and CO2

reductions across California, U.S., EU, and Japan

10 14

19 )

(1.8 billion gallons)

(0.5 billion gallons)

26 billion liters (7 billion gallons

6.9 billion liters

1.7 billion liters

10 14

19

Predicting Fuel Used for AC •

– 2) – –

State A

TMY MonthT C

T

H PPD Time PPD

VMT w/ AC

MPG

MPG

Gal for AC/ Reg Gal/

State

Apr

July

0

0 0

5

5

10

10

15

15 20

25

(C) i

f

Model 0

5

10

15

20

25

ii

ime

1500 ( )

i(

)

ii

i

Use Multiple Models/Inputs/Data Sets Environmental Conditions (Temp, RH, W/mThermal Comfort Model Vehicle Simulations (Fuel Economy Reduction with AC)

City B

City X

City A

w/ AC

w/o AC

veh

Total

12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm 10pm-12am Jan

Feb

Mar

May

June

Aug

Sept

Oct

Nov

Dec Temper atur e n Denver, CO

Mon

th

Ti me o Day

Thermal Comfort

12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm 10pm-12am Hour of the Day

Perc

enta

ge o

f Tra

vel O

ccur

rng

durn

g th

at T

0.0

1.0

2.0

3.0

4.0

5.0

6.0

1000 2000 2500 3000 3500 Compressor Speed rpm

Sys

tem

Pow

er C

onsu

mpt

on k

W

Fixed D sp 210 Fixed D sp 180 Var D sp 125 Defrost 210 Defrost 180 Defrost 125

Model Updates• Updates to U.S. study, Summer 2003

– Mean Radiant Temperature varies with vehicle type (car, truck) • Therefore usage PPD varies with type

– Thermal comfort: use one assumption for clothing and soak (MRT) – Include demisting – AC power consumption = f(type, compressor speed)

State A

TMY MonthT C

T

H PPD Time PPD

VMT w/ AC

MPG

MPG

Gal for AC/ Reg Gal/

State

Demist

City B

City X

City A

w/ AC

w/o AC

veh

Total

Environmental Conditions: Phoenix, AZ: Temperature

State A

TMY MonthTC T

H PPD

PPD VMT

MPG

MPG AC/ Reg

Jan Feb Mar Apr

June

Aug Sept Oct Nov Dec 10

10

15

15

15

15

20

20

25

25

30

35Mon

th

Temperature, humidity,

solar radiation

City B

Time

City X

City A

w/AC

w/AC

w/o AC

Gal for veh

Tot Gal /State

12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm10pm-12am

May

July

Temperature (C) in Phoenix, AZ

Time of Day

Mean Radiant Temperature Models

• MRT varies with vehicle type (car, truck) • Vehicle data used to generate models

• Ford Crown Victoria • Ford Explorer (White) • Ward Atkinson – Phoenix 2002 • Plymouth Breeze • Ford Explorer (Black) • Bill Hill – GM Data • Jeep Grand Cherokee • Lincoln Navigator

• Dodge Grand Caravan

Models

MRT(car, time) = * Radiation(t)/1000W/m2 + Tambient(t)

MRT(truck, time) = 24°C 2 + Tambient (t)

27°C

* Radiation(t)/1000W/m

Mean Radiant Temperature by City

Jan

Feb

Mar

Apr

June

Aug

Sept

Oct

Nov

Dec 10

10

20

20

20

20

30

30

30

40

50

60

Mean Radiant Temperature (C) in Phoenix, AZ M

onth

May

July

12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm 10pm-12am Time of Day

Thermal Comfort Model:Percent of People Using AC

-3 -2 -1 0 1 2 30 10 20 30 40 50 60 70 80 90

100

PPD

Thermal Comfort Model,

+ 3 + 2 + 1 0

Slightly Cool - 2 l - 3 ld

PMV Thermal Sensation

State A

TMY MonthTC T

H PPD

PPD VMT

MPG

MPG AC/ Reg

Thermal Sensation Vote

Warm Cool

PPD from PMV

Hot Warm

Slightly Warm Neutral

- 1 CooCo

City B

Time

City X

City A

w/AC

w/AC

w/o AC

Gal for veh

Tot Gal /State

AC Usage for CoolingPredicted Percent Dissatisfied (%) in Phoenix, AZClothing: 0.6, Velocity: 0.1, MRT: Ambient+Rise

Dec 10 1M

onth

Nov

Oct

Sept

Aug

July

June

May

Apr

Mar

Feb

Jan

1

1 1

10

10

10

20

20

30

30

40

40

50

60

70

80

90

AC Off

100% of People Have AC On

12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm 10pm-12amTime of Day

AC Usage for DemistingAC used for demist if:

Temperature is between 1.7-12.8°C (35-55°F), and Relative Humidity > 80% M

onth

Demist Percent Usage in Brussels, BEL

Dec

Nov

Oct

Sept

Aug

July

June

May

Apr

Mar

Feb

Jan

1

1

10

No Demist Usage

20

20

30

30

40

40

50

50

60

60

70

70

80

80

90

90

100% Demist Usage 12-6am 6-9am 9am-1pm 1-4pm 4-7pm 7-10pm 10pm-12am

Time of Day

Vehicle Usage with Time of Day, MonthState A

TMY MonthTC T

H PPD

PPD VMT

MPG

MPG AC/ Reg

City B

Time

City X

City A

w/AC

w/AC

w/o AC

Gal for veh

Tot Gal /State

10

15

20

25

70% Daily Travel

Per

cent

age

of T

rave

l Occ

urrin

gin

that

Mon

th

9

8

7

6

5

4

3

2

Summer Months: May ­

September

Average

Per

cent

age

of T

rave

l Occ

urrin

gdu

ring

that

Tim

e

12-6am 6-9am9am-1pm1-4pm 4-7pm 7-10pm10pm-12am

1

00 2 4 6 8 10 12 Hour of the Day Month of the Year

0

5

15

27

17

25

18

31

26

49

40

23

50

17

26

42

40

25

21

41

32

23

19

26

19

38

18

52

33

2024

37

28

50

3033

3225

23

26

69

41

57

2129

58 43

43

6

Percent of Time AC is On: Cooling + Demist

State A

TMY MonthTC T

H PPD

PPD VMT

MPG

MPG AC/ Reg

City B

Time

City X

City A

w/AC

w/AC

w/o AC

Gal for veh

Tot Gal /State

10 14

19

15

27

17

25

18

31

26

49

40

23

50

17

26

42

40

25

21

41

32

23

19

26

19

38

18

52

33

20 24

37

28

16

50

3033

3225

23

26

69

41

57

28

21

2129

58 43

43

6

ifi i

Percent of Time AC for Cooling

+ Dehumid cat on

6.3 to 17.9 17.9 to 19.6 19.6 to 22.9 22.9 to 25.1 25.1 to 25.9 25.9 to 28.4 28.4 to 32.1 32.1 to 37.8 37.8 to 41.4 41.4 to 49.2 49.2 to 57.3 57.3 to 69.3

23

24

23

21

23

25

26

27

27

2524

25

23

27

24

25

23

26

2525

24

26

25

27

26

24

23

26

27

2527

2525

25

27

26

27

2422

30 27

17

Climate during AC UseTemperature, Humidity

10 14

19

27

2624

25

27

23

24

23

21

23

25

26

27

27

25

27

24

25

23

27

24

25

23

26

25

26

25

24

26

25

27

26

2424

23

26

23

27

2527

2525

25

25

27

26

27

25

24

2422

30 27

27

17

Average Temperature During AC Use (C)

16.9 to 22.8 22.8 to 23.5 23.5 to 24.1 24.1 to 24.6 24.6 to 24.9 24.9 to 25.1 25.1 to 25.5 25.5 to 26.2 26.2 to 26.7 26.7 to 26.7 26.7 to 27.3 27.3 to 30.2

U.S. Average: 25°C

50

77

58

70

77

37

69

74

63

70

71

71

56

69

72

67

52

42

69

31

76

67

74

47

75

74

71

71

81

7569

7471

37

71

73

74

80

4768

32 72

76

67

Climate during AC UseTemperature, Humidity

10 14

19

77

73 57

50

77

77

58

70

77

37

69

74

63

70

71

71

56

69

72

67

52

42

69

31

76

67

74

47

75

74

7371

57

71

71

81

7569

7471

37

71

73

74

80

72

73

4768

32 72

76

67

Average Relative Humidity During

AC Use (%)

31 to 47 47 to 56 56 to 67 67 to 69 69 to 70 70 to 71 71 to 72 72 to 73 73 to 74 74 to 76 76 to 77 77 to 81

U.S. Average: 66% RH

Percent of Time AC in Use

Cooling and Demisting

ingdom

i

land

I land

Fi

ic

lgaria

i

AC is ii ist

United K

Turkey

Sw tzerland

Sweden

Spain

Romania

Portugal

Po

Norway

Netherlands

Japan

Italy

re

Hungary

Greece

Germany

France

nland

Denmark

Czech Republ

Bu

Belg um

Austria

Percent of Time n Use

Cool ng + Dem

19.4 to 28.6

28.6 to 32.7

32.7 to 37.0

37.0 to 41.5

41.5 to 44.2

44.2 to 44.7

44.7 to 45.9

45.9 to 50.6

50.6 to 58.8

Fuel Economy Impact: Vehicle Simulations

State A

TMY MonthTC T

H PPD

PPD VMT

MPG

MPG AC/ Reg

City B

Time

City X

City A

w/AC

w/AC

w/o AC

Gal for veh

Tot Gal /State

US Car US Truck EU Vehicle Fuel Economy no AC 22.0 18.8 30.4

Fuel Economy with AC 18.0 16.2 27.3 Fuel Economy defrost 21.1 18.1 29.0

US Car US Truck EU Vehicle FE Drop with AC 18% 14% 10%

FTP drive cycle FE Drop with defrost 4% 4% 4% Hot initial conditions

US car and truck based on existing fleet

0

1

4

4

1

6

2

15

5

1

3

1

9

3

3

10

12

1

1

7

1

1

1

6

1

2

9

1

4

4

2

59

1

3

1

6

12

324

3 2

4

0

Vehicle RegistrationsState A

City B TMY MonthTC

T

H PPD Time

PPD

City X

City A

VMT w/AC

MPG w/AC

MPG w/o AC

Gal for AC/veh Reg

Tot Gal /State

10 14

194

4

3

0

1

4

4

1

6

2

15

5

1

3

1

9

3

3

10

12

1

1

7

1

1

1

6

1

2

4

49

1

4

5

4

32

59

1

3

1

6

12

1

3

324

3 2

4

0

Million Vehicle Registrations

0.4 to 0.7 0.7 to 1.0 1.0 to 1.4 1.4 to 1.8 1.8 to 2.8 2.8 to 3.3 3.3 to 3.9 3.9 to 4.4 4.4 to 6.0 6.0 to 9.2 9.2 to 12.5 12.5 to 23.9

Total Million

Vehicles US 213.0

Distance Traveled per Year Sources: • 2002 World Road

Statistics from the International Road Federation

• International Road Traffic and Accident Database

• Ward’s Automotive Yearbook, 2001

EU and Japan

Spain

l

Italy

Fi

ic

l

United Kingdom

Turkey

Switzerland

Sweden

Romania

Portugal

Poland

Norway

Nether ands

Japan

Ireland

Hungary

Greece

Germany

France

nland

Denmark

Czech Republ

Bulgaria

Belgium

Austria

Vehic e Kilometers Traveled

6500 to 9803

9803 to 10738

10738 to 13321

13321 to 14964

14964 to 17537

17537 to 20015

U.S.: • Car: 11,850 miles

(19,070 km) • Truck: 11,958

miles (19,244km)

7

37

78

64

9

187

43

735

179

17

127

15

66

109

229

273

61

52

167

22

40

12

219

17

85

144

86186

21

118

176

9575

142242

26

68

68

251

753

76730

216 86

167

1

National Fuel Used for AC

State A City B

TMY MonthTC T

H PPD Time

PPD

City X

City A

VMT w/AC

MPG w/AC

MPG w/o AC

Gal for AC/veh Reg

Tot Gal /State

• 7.0 billion gallons used forair conditioningannually

• 5.5% total fuel consumption

• 62 billion kg CO2 • 9.5% imported

crude oil

10 14

19

238

7

37

78

64

9

187

43

735

179

17

127

15

238

66

109

229

273

61

52

167

22

40

12

219

17

85

144

86 186

21

118

86

176

9575

142242

26

68

68

251

753

19

61

76730

216 86

167

1

Million Gallons Cooling &

Dehumidification

1 to 17 17 to 26 26 to 52 52 to 68 68 to 78 78 to 86 86 to 142 142 to 176 176 to 216 216 to 242 242 to 730 730 to 753

Total Fuel Use for AC for Cooling and Demisting

i i

Swi

Spain

Pol

Italy

I

ic

lgaria

Bel

i

8 to 12

Totals Dehumid +

Cooling Billion

Gallons Billion Liters

Billion kg CO2

Percent of Total Consumption

EU 100% Market 1.8 6.9 16.0 3.2% Japan 100% Market 0.45 1.7 4.0 3.5%

Un ted K ngdom

Turkey

tzerland

Sweden

Romania

Portugal

and

Norway

Netherlands

Japan

reland

Hungary

Greece

Germany

France

Finland

Denmark

Czech Republ

Bu

gium

Austria

Million Gallons Cooling & Dehumid fication

12 to 14

14 to 16

16 to 23

23 to 25

25 to 41

41 to 53

53 to 75

75 to 258

258 to 303

303 to 450

450 to 450

-

AC

-

1

2

3

4

5

6

7

8

65% 70% 80% 85% 95% 100% 105% 0

10

20

30

40

50

60

70

U.S. Fuel Saved & CO2 Reduced by Reducing AC Consumption

10 14

19

5.5% Vs. Total Consump.

3.6%

0.5 0.9

1.3 1.7

2.5

Consumption

0.1

2.1 CO2 Reduced

AC Fuel Saved

75% 90%

AC Power Consumption: Percent of Baseline

Bill

ion

Gal

lons

Bill

ion

kg C

O2

5.4

9.4

6.4

5.0

6.0

11.9

10.1

17.9

14.2

8.3

16.3

7.5

9.4

7.7

14.0

8.7

8.7

16.4

12.5

9.2

7.1

10.0

6.97.1

16.6

11.9

7.97.4

10.6

17.8

12.1

9.99.3

8.7

28.2

8.311.0

22.8 14.7

15.3

0.4

Fuel Saved per Vehicle by Climate30% Reduction in AC Power

10 14

19

13.1

7.6

10.9

9.4

14.0

21.9

5.4

9.4

6.4

5.0

6.0

11.9

10.1

17.9

14.2

8.3

16.3

7.5

9.4

7.7

14.0

8.7

8.7

16.4

12.5

9.2

7.1

10.0

6.9

13.1

7.1

16.6

11.9

7.9 7.6

7.4

10.6

6.6

17.8

10.912.1

9.99.3

8.7

9.4

28.2

14.0

21.9

10.2

7.9

8.311.0

22.8 14.7

15.3

0.4

Gallons Saved /Vehicle/Year,

30% Reduction in AC Power

0.4 to 6.6 6.6 to 7.5 7.5 to 7.9 7.9 to 8.7 8.7 to 9.4 9.4 to 10.1 10.1 to 11.9 11.9 to 13.1 13.1 to 14.7 14.7 to 16.6 16.6 to 21.9 21.9 to 28.2

-0

2

4

6

8

10

12

14

65% 70% 75% 85% 90% 100% 105%

li /

i l/

li /

Per Vehicle Fuel Saved by Reducing AC Consumption

10 14

19

2.0

3.9

5.6

7.5

9.4

11.0

0.3

80% 95%

AC Power Consumption: Percent of Baseline

Gal

lons

Sav

ed/Y

ear

Car: Base ne Use 33.7 gal year

Truck: Basel ne Use 26.8 ga year

Average: Base ne Use 30.8 gal year

U.S. Fuel Savings Taking into Account New Technology Penetration

• Assumptions– 15% and 30% reductions 6

15%

AC Power

AC Power

3.7 bil gal/yrSaved by 2025

Reduction in

Reduction in30%

in AC power – Power reductions begin 5

in 2010 4

– Fleet grows through time (DOE’s Vision model) 3

• 234 million in 2010 2

• 293 million in 2050 1

– Fleet turnover in 16 years 02010 2015 2020 2025 2030 2035 2040 2045 2050

Time (year) – VMT increases over time • 13,500 miles in 2010 • 19,950 miles in 2050

Bill

ion

Gal

lons

per

Yea

r Sav

ed

Per Vehicle Savings from an Improved MAC

$0

Savi

ngs

from

an

Impr

oved

HFC

-134

a A

/C S

yste

m(2

004

$)

- / -­ One A/

­­-

$50

$100

$150

$200

$250

$300

$350

$400

$450

Assumptions: 30% reduction in A C energy 11 gallons of fuel per year saved

C service avoided in year 8 Cost of service charge = $107 Cost of fuel = 1.75 $/gal Costs rise at rate of inflation

0 2 4 6 8 10 12 14 16

Vehicle Life (years)

A l

70% 80% 85% 95%

i li

Billio

n G

allo

ns

-

2

4

6

8

10

12

14

16

18

il i

Bil

EU Fuel Saved by Reducing AC Power Consumption

3.2% Vs. Total Consump.

2.2%

0.02 0.09

0.19 0.28

0.37 0.46

0.56

EU AC Consumption

C Fue Saved

CO2 Reduced

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

65% 75% 90% 100% 105%

AC Power Consumpt on: Percent of Base ne

Billio

n kg

CO

2

EU AC Consumpt on EU AC Fue Sav ngs

kg CO2 Saved

i

l

65% 70% 75% 80% 85% 90% 95% 100% 105%

i line

Billio

n G

allo

ns

-

Billi

Japan Fuel Saved by Reducing AC Power Consumption

3.4% Vs. Total Consump.

2.4%

0.005 0.02

0.05 0.07

0.09 0.11

0.14

Japan AC Consumpt on

AC Fue Saved

CO2 Reduced

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

AC Power Consumpt on: Percent of Base

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

on k

g C

O2

Conclusions

• MAC fuel use & CO2 emissions are strong functions of:– Vehicle design – Vehicle use – Environment

• Solutions to reduce fuel consumed by MACs – Reduce the thermal load – improve vehicle design – Improve delivery – design for occupant thermal comfort – Improve equipment – Educate consumers on impacts of driver behavior on MAC fuel

use

Conclusions (cont.)• Thermal comfort-based AC fuel use prediction

US EU Japan AC Fuel Use, Billion Gallons 7.0 1.82 0.45

AC Fuel Use, Percent of Total Consumption 5.5% 3.2% 3.4%

• Reducing AC fuel use has the potential to greatly benefit the nation • Reduce imported oil • Reduce CO2

• Per vehicle savings allow calculation of payback time 30% Reduction in Power Units US California EU Japan

Savings per Vehicle gal/year 11.0 11.0 2.5 2.2 Reference Total Consumption gal/year 30.8 30.5 8.0 7.2 Savings of Total Consumption % 2.0% - 1.0% 1.0%

Fuel Saved Bil Gallons 2.5 0.26 0.56 0.14 Fuel Saved Bil Liters 9.5 1.0 2.1 0.5

Emissions Reduced Bil k G CO2 22.1 2.3 4.9 1.2

• Impact of incremental reduction in AC power: states, nations, world

Fuel Savings across the World

Billion Gallons: Savings with 30% Drop in AC Power

CO2 Reduction across the World

Billion kg CO2: Reduction with 30% Drop in AC Power

Thank you!Thank you!• John Rugh

– Ph: 303-275-4413 – Email: john_rugh@nrel.gov

• Valerie Hovland – Email: vhovland@mesoscopic.com

• Stephen Andersen – Ph: 202-343-9069 – Email: andersen.stephen@epa.gov

Back Up

Why So Much Fuel for A/C?

150 Watts

Metabolic Heat

A/C Cooling 3-6 kWth!

Generation

Cities Used from TMY Data Base

• Plymouth Breeze• July 12• Golden, CO

• Jeep Grand Cherokee• July 12• Golden, CO10

20

30

40

50

60

70

80

90

5:30 7:30 9:30 11:30 13:30 15:30 17:30

Time

Tem

pera

ture

(C)

TrimSeatAirGlazingIPHeadliner AmbientModel

10

20

30

40

50

60

70

80

90

5:30 7:30 9:30 11:30 13:30 15:30 17:30

Time

Tem

pera

ture

(C)

TrimSeatAirGlazingIPHeadliner AmbientModel

Car & Truck MRT

Vehicle Modeling in ADVISOR

• 115 kW SI engine, 1300 kg

• 144 kW SI, 1924 kg

icle • 91 kW compression

ignition diesel, 1220 kg

gasoline equivalent fuel consumption

2 from fuel consumption

• 2/liter fuel 1000 2000 3000 40000

50

100

150

200

250

300

350

)

(

ici

• U.S. Car

• U.S. Truck

• EU Veh

• Fuel economy expressed in

• CO emissions determined

2.33 kg CO

Speed (rpm

Torq

ueN

m)

Engine Eff ency Mercedes 1.7L Diesel Engine f/ ORNL

0.05 0.1 0.15

0.2 0.25

0.3 0.35

0.35 0.4 0.45

Series5

AC Modeling

• HFC-134a • U.S. trucks: 210 cc fixed • U.S. cars: 180 cc fixed • EU vehicle: 125 cc

variable displacement• Compressor power

consumption based onDelphi compressor curves

• Total power = Pcompressor + Pblower

1000 1500 2000 ( )

i)

Fi iFi i

i

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2500 3000 3500 Compressor Speed rpm

Sys

tem

Pow

er C

onsu

mpt

on (k

W0.0

0.7

1.3

2.0

2.7

3.4

4.0

4.7

5.4

Hor

sepo

wer

xed D sp 210 xed D sp 180

Var D sp 125 Defrost 210 Defrost 180 Defrost 125

• Pblower = 120 W Curves based on work by Forrest at Delphi

• Engine speed/compressor • Cooling mode: 27°C, 60% RH speed ratio = 0.64 • Demist mode: 16°C, 80% RH

Conservative Estimate ofFuel Used for AC

• Fanger’s thermal comfort model excludes: –Sun hitting a driver –Thermal asymmetry –Sitting on a hot seat –High humidity impacts

• Model excludes AC use due to–Automatic Temperature Control

• EU compressor power

Series5

Incremental Reduction in AC Power

1000 1500 2000 3500 )

i) .

Fi iFi iFi i

85% of Baseline Power

70% of Baseline Power

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2500 3000 Compressor Speed (rpm

Sys

tem

Pow

er C

onsu

mpt

on (k

W

0.0

0.7

1.3

2.0

2.7

3.4

4.0

4.7

5.4

Hor

sepo

wer

xed D sp 210 xed D sp 210 * 0.85 xed D sp 210 * 0.7

EU/Japan Per Vehicle Fuel Saved by Reducing AC Consumption

65% 70% 80% 90% 95% 105% i li

Gal

lons

Sav

ed/Y

ear/V

ehic

le

Lite

rs S

aved

/Yea

r/Veh

icle

li l

li l

0.08

0.4

0.8

1.2

1.6

2.1

2.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

75% 85% 100% AC Power Consumpt on: Percent of Base ne

0.0

2.0

4.0

6.0

8.0

10.0 EU Base ne: 8.0 gal ons

Japan Base ne: 7.2 gal ons